How to Fix a Running Toilet (Landlord Guide)

A running toilet isn't just annoying—it's expensive. A single constantly running toilet can waste 200 gallons or more per day, adding roughly $200–$400 per year to your water bill. Multiply that across multiple units and the cost adds up fast. The good news: most running toilets are caused by one of three simple issues you can fix yourself in under 30 minutes with basic tools and $15–$50 in parts. This guide walks you through diagnosing the problem and making the repair so you can stop the waste and the bills.

Diagnose the Problem

Before you buy parts or start disassembling, identify which of these three common causes is behind your running toilet:

1. Faulty Flapper

The flapper is the rubber seal at the bottom of the tank that lifts when you flush and drops back to seal the drain. If it's cracked, warped, or covered in mineral buildup, water leaks continuously into the bowl. You'll often hear a steady trickle or see a slight ripple in the bowl water. This is the most common cause—and the easiest fix.

2. Bad Fill Valve

The fill valve controls how much water enters the tank after a flush. If the float is set too high or the valve is worn, water overflows into the overflow tube and runs into the bowl. You'll hear a hissing or trickling sound that continues after the tank appears full. The water level may also rise above the overflow tube.

3. Overflow Tube Issue

The overflow tube is the vertical pipe in the center of the tank. If the refill tube (the small flexible hose) is disconnected or pointed outside the overflow tube, water can spray or drip in ways that trigger continuous running. Less common, but worth checking if the flapper and fill valve look fine.

What You'll Need

Tools

0 / 3

Adjustable wrench or channel locks
Sponge or towel
Bucket (optional, for catching water)

Parts (buy as needed)

0 / 3

Universal toilet flapper ($8–$15)
Fill valve kit ($15–$30)
Flapper chain (often included with flapper)

Step-by-Step Fix

Step 1 of 50 completed

Turn Off the Water

Locate the shutoff valve on the wall or floor behind or beside the toilet. Turn it clockwise until it stops. Flush the toilet once to drain most of the water from the tank. Use a sponge to soak up any remaining water so you can work comfortably.

DIY vs Pro Cost Comparison

Approach	Cost	Time
DIY (flapper only)	$10–$20	15–20 min
DIY (flapper + fill valve)	$25–$50	30–45 min
Plumber	$100–$250	1–2 hours (incl. travel)

When to Call a Plumber

Most running toilets are DIY-friendly, but call a professional if:

You've replaced both the flapper and fill valve and it still runs—there may be a crack in the flush valve or tank.
Water pools around the base of the toilet—indicates a wax ring or tank-to-bowl seal failure.
The toilet rocks when you sit on it—the flange or floor may be damaged.
You're not comfortable working with plumbing or don't have time—a plumber can resolve it quickly.

Frequently Asked Questions

How much does a running toilet cost in water bills?

A constantly running toilet can waste 200 gallons or more per day, adding roughly $200–$400 per year to your water bill depending on local rates. Fixing it quickly pays for itself many times over.

Can I fix a running toilet without a plumber?

Yes. Most running toilets are caused by a worn flapper or faulty fill valve—both are simple DIY fixes that take 15–30 minutes. Universal replacement parts cost $10–$25 and require no special tools.

How do I know if it's the flapper or the fill valve?

If water runs continuously into the bowl, the flapper is likely not sealing. If the tank refills and then water runs into the overflow tube (you'll hear a hissing or trickling sound), the fill valve or float is the problem.

When should I call a plumber for a running toilet?

Call a plumber if you've replaced the flapper and fill valve and it still runs, if you see water pooling around the base, if the toilet rocks when you sit on it, or if you're uncomfortable working with plumbing.

Skip the guesswork. Let AI handle it.

PropFix diagnoses issues instantly, walks you through DIY repairs step-by-step, and documents everything for your records.

Try PropFix Free

Free for your first property. No credit card required.